Pilots of aircraft communicate with air traffic controllers (“ATCs”) through voice radio communication or through electronic messages. Some avionics systems include functionality that enables a pilot of an aircraft to request clearance from a ground ATC located at an air traffic control center by sending a clearance request message to the ATC. As used in this application, a clearance request “message” is an electronic message sent between an aircraft and an ATC control center using a data communication system. This differs from a “voice” clearance request that a pilot makes by speaking and which is communicated between an aircraft and an ATC control center using a voice communication system. The avionics system is located in the aircraft and communicates with the ATC using one or more data links that are established between the avionics system and the ATC. The data link is typically established between the aircraft avionics system and the ATC control center using very high frequency (“VHF”), high frequency (“HF”), or satellite communication (“SATCOM”) radio communications using Aircraft Communications Addressing and Reporting System (“ACARS”) or Aeronautical Telecommunications Network (“ATN”). The electronic messages are sent across this data link. The ATC communicates a response to the request for clearance by sending a response message to the avionics system using the data link. The response message is also an electronic message that is communicated across the data link. The ATC can send an affirmative response message when the ATC grants the request for clearance or can send a negative response message when the ATC denies or delays the request for clearance.
One or more applicable policies dictate that particular clearances must be requested and granted before an aircraft takes off, while others must be requested and granted while the aircraft is airborne and or after the aircraft has landed. Clearances that must be requested and granted before an aircraft takes off are referred to here as “pre-flight” clearances. Clearances that must be requested and granted while an aircraft is airborne are referred to here as “in-flight” clearances. Clearances that must be requested and granted after the aircraft has landed are referred to here as “post-flight” clearances. Examples of pre-flight clearances include those relating to push back, taxi, and takeoff. This list is not exhaustive and other types of pre-flight clearances exist. Examples of in-flight clearance clearances include those relating to changing altitude, maintaining altitude, changing direction or heading, maintaining direction or heading, changing speed, maintaining speed, crossing a particular waypoint position, following a particular route, proceeding to a particular position, resuming normal speed, confirming position, confirming altitude, confirming speed, and confirming next waypoint. This list is not exhaustive and other types of in-flight clearance clearances exist. Examples of post-flight clearances include those relating to taxing-in and parking at the gate. Clearance request messages and response messages are typically sent across the data link, though voice radio communication between the pilot and/or flight crew and the ATC can also be used to request and respond to clearance requests.
Scenarios occur in which a pilot and/or flight crew are distracted in the cockpit, such that they neglect to request a particular clearance from the ATC before initiating aircraft movement which, under an applicable policy, requires the clearance to be granted before the movement is initiated. For example, there have been cases reported in the Aviation Safety Reporting System (“ASRS”) database where pilots have inadvertently taxied without taxi clearances and taken off without takeoff clearances, only to realize what happened after completing the taxi and takeoff respectively. Aircraft movements on the ground that are made without the appropriate clearance may lead to collisions or other accidents or lead to other adverse effects.